feat!: add function calling support to client.chat() & client.chat_async()

BREAKING CHANGE: Too many to count in this version. Check the README examples.

CONTRIBUTING.md

@@ -4,7 +4,10 @@
   - [Requirements](#requirements)
   - [First setup](#first-setup)
   - [Optional requirements](#optional-requirements)
+- [Local Development](#local-development)
   - [Test](#test)
+- [Documentation](#documentation)
+  - [Readme](#readme)
 - [Code of Conduct](#code-of-conduct)
 - [Commit Message Format](#commit-message-format)
 
@@ -41,6 +44,8 @@ Then edit the `.env` file to set your `MISTRAL_API_KEY`.
 - [cargo-llvm-cov](https://github.com/taiki-e/cargo-llvm-cov?tab=readme-ov-file#installation) for `make test-cover`
 - [cargo-watch](https://github.com/watchexec/cargo-watch#install) for `make test-watch`.
 
+## Local Development
+
 ### Test
 
 ```sh
@@ -53,6 +58,16 @@ or
 make test-watch
 ```
 
+## Documentation
+
+### Readme
+
+> [!IMPORTANT]
+> Do not edit the `README.md` file directly. It is generated from the `README.template.md` file.
+
+1. Edit the `README.template.md` file.
+2. Run `make readme` to generate/update the `README.md` file.
+
 ## Code of Conduct
 
 Help us keep this project open and inclusive. Please read and follow our [Code of Conduct](./CODE_OF_CONDUCT.md).